Esters



Patented st. 30,1945 v UNITED STATES PATENT OFFICE!) ESTERS Donald JohnLoder, Wilmington, per, asslgnor to E. I. du Pont de Nemours & Company,Wilmington, Del., a corporation of Delaware No Drawing. ApplicationJanuary 20, 1943, Serial No. 472,993

3 Claims.

The present invention relates to new materials and to methods fortheirpreperation, and more particularly, to the polyhydric alcoholesters of alkoxy and alkoxy methylene substituted acetic acids andmethods for their preparation. The application is a continuation in partor copending application 8. N. 340,473, filed June 14, 1940.

An object or the present invention is to provide new compositions ofmatter and processes for their. preparation. A further object of theinvention is to provide monoand poly-ethylene glycol and monoanddi-glycerol and triglyceryl esters or substituted glycolic acids,together with processes for their preparation. Yet another ob- Ject ofthe invention is to provide a process for the preparation of glycolmonoand di-glycolates and glycerol monoand di-glycolates by esterlfyingsubstituted glycolic acid with glycols and glycerol, respectively. Aiurther'object of the invention is to providemonoand di-substitutedglycolic acid esters of ethylene glycol and polyethylene glycols and themono.-, diand triglycerides of substituted glycollc acids, together withprocesses for their preparation. Other obiects andadvantages of theinvention will hereinatter appear. These objects, as well as otherswhich will apparent as the description proceeds, maybe accomplished byreacting a lower alkyl ester oi! an oily-substituted acetic acid with apo yhydrlcalcohol under conditions favorable to the interchange ofalcohol radicals This interchange of alcohol radicals is effected byheating the alcohol and ester together, preferably in the presence oi.alkaline alcoholysis catalysts. The ester interchange proceeds morereadily it the alcohol selected for reaction with the ester boils at ahigher temperature than the alcohol liberated by the interchange,because the latter alcohol is then more readily removed from the zone ofreaction, for example, by distillation.

The ester interchange process described above may be employed for thepreparation or either the monoglycolates or the polyglycolates, forexample, when it is desired to prepare ethylene one mole of glycerolisreacted'with one, two, or 55 three moles of an ester of glycolic acid.The

process is applicable generally to the preparation ol polyhydricalcohol, monoand po y-fllycolates, monoand poly-alkoxy glycolates andmonoand poly-alkoxy methoxy glycolates irom the polycrmocmocrni coon Themethyl, ethyl, propyl,isopropyl, butyl, isobutyl, amyl, etc., esters ofthis acid, may be reacted with the polyhydric alcohols generally, such,for example, as: the glycols, e. g., ethylene glycol, propylene glycol,butylene glycol, amylene glycol, diethylene glycol, trimethylene glycol,octadecanediol, tetramethylene glycol, hexamethylene glycol, or thealcohols containing more than two hydroxyl groups, such as glycerol,diglycerol, trlglycerol; trimethylol methane and trimethylol propane:sugars, such as, dextrose, sucrose, xylose, galactose, fructose,maltose, and mannose; and the sugar alcohols, such as sorbitol,mannitol, and dulcitol; as well as castor oil (glyceryl triricinoleate),hydrogenated castor oil, (hydroxy stearin) and like long chainpolyhydric alcohols.

This invention likewise includes esters of glycolic acid, alkoxyandalkoxy methoxy-acetic acids with ether alcohols, i. e., polyhydricalcohols having at least one tree hydroxyl group, one or more hydroxylgroups being etherifled. Examples of such ether alcohols include themonoalkyl ethers ofethylene glycol, such as the monomethyl, -ethyl,-propyl or -butyl ethers-of ethylene glycol, propylene glycol, etc.Esters or this class would be, e. g., ethylene glycol monomethyl etherglycolate, ethylene glycol monoethyl ether glycolate, ethylene glycolmonomethyl ether methoxy acetate, CI-Ia(OCHs)CO0CHaCl-I:OCI-Ia, andethylene glycol moriomethyl ether methoxy 4o methoxy acetate,

CH2(OCHrOCH3).COOCHrCI-I2OCHa The monoand di-glycolates of themonoglycerides are likewise included, e. g., the monoglyce- 45 lates ofthe monoglycerides,

' cnnomcoocmcnoncmoa in which R is methyl, ethyl, propyl, butyl, etc.The monoglycerides otstearic acid, oleic acid, 50 palmitlcacid, etc, maybe used for the preparation or these monoand di-glycolates.

'Polyhydric alcohol esters as well as ether alcohol esters ofsubstituted glycolic acids may likewise be prepared by the aforesaidester interchange process. For example, such esters or the followingacids are also included in the present invention: the alkoxy aceticacids,

CH2 (OR) COOH e. g. ethoxy-, pr0p0xy-. iSO-butoxy-acetic acids, etc.;the alkoxy alkoxyacetic acids,

cm oaoa coorr e. g., ethoxy methoxy-, propoxy methoxy-, isobutoxymethoxy-aoetic acids, etc.; and the carboalkoxy methoxy methoxy aceticacids,

CH2 (OCHaOCHrCOOR) COOH e. g., carbomethoxy methoxy methoxy acetic acidor carboethoxy methoxy methoxy acetic acid, the latter compounds may beprepared by reacting glycolic acid with formaldehyde or methylal inaccord with the process described in the copend-- cohol with theglycolic acid. There appears to be one exception to this, in that, dueto the dehydrating characteristics of glycolic acid, it does not reactreadily with glycerol but forms acrolein at the expense or the glycerolester and, consequently, simple esteriflcation should preferably not beemployed when the glycerol esters of glycolic acid are desired.

The invention likewise provides another ester interchange process forthe preparation of esters of glycolic acid. This process involves theinteraction of a polyhydric alcohol or ether alcohol with glycolide,which may be considered to be a olyester of glycolic acid. This reactionmay be effected by first forming the glycolide (prepared, e. g., in theusual mannenby heating the glycolic acid to drive off all the water),and subsequently reacting the glycolide (which may be present as adiglycolideor as a polyglycolide) with the polyhydric alcohol. If apartially dehydrated glycolic acid is used, e. g., a diglycolide orpolyglycolide in the presence of free glycolic acid, the initialreaction is carried out under reflux and then water of esterification,of free glycolic acid and glycol removed with the aid of heat, eitherwith or without a water'carrler, such as,

The heat was discontinued and any low boiling material which remainedwas removed by vacuum distillation. (If desired the color of the productmay be improved by treatment with 2 per cent of. its weight of astandard decolorizing charcoal.

For most purposes, however,- the color of the untreated ester wassatisfactory.)

(B) T0310 part (5 moles) of ethyleneglycol, contained in a suitableE-necked flask equipped with an efllcient stirrer and reflux condenser,

' wasadded 290 parts (5 moles) of powdered polytoluene. Ordinarily, thisester interchange may be conducted under atmospheric pressure,particularly with the higher boiling polyhydrlc a1- cohols, although iflow boiling alcohols are employed, autogenous pressure or appliedpressures of from 5 to 600 atmospheres may be employed. The moredetailed practice of the invention is illustrated by the followingexamples in which parts given are by weight unless otherwise stated.There are, of course, many forms of the invention other than thesespecific embodiments.-

ExAMPLs I.-ETHYLENE GLYCOL MONOGLYGOLATE (A) To 2250 parts (25 moles) ofmethylglycolate was added 1550 parts (25 moles) of ethylenc glycol and,as catalyst, a solution of 3.0 grams of sodium in '1 grams of methanol(30% sodium methoxide solution). This mixture was refluxed under afractionating column, fitted with a distilling head arranged forcontrolled reflux, until the head temperature had receded to 64-65 C.The methanol was removed as rapidly as possible at the head of thecolumn, the head temperature being carefully maintained between 64 C.and 66 C. The refluxing and the collecting of the methanol werecontinued for approximately ten hours, at the end of which timeapproximately 800 grams (25 moles) of methanol had been. collected.

glycolide, prepared by completely dehydrating glycolic acid at elevatedtemperatures (100-220 The temperature of the reaction mixture 200 0.,preferably between l-200 C., for a period of approximately flve hours.

In both A and B the reaction mixture was cooled, and the productobtained was a pale amber-colored liquid which contained 98 to 99 percent. of glycol monoglycolate.. The yield was substantiallyquantitative, based on either the glycol or glycolate; sp. gr. was 1.28360 F./60 F- and the saponiflcation number was 460.

EXAMPLE II.--E'.rr-rYi.nNa DIGLYCOLATE The conditions and procedure arethe same as Example I.

Quantities Parts Moles Eth lene glycol 930 15 Met ylglycolate 2,700 30Anh drous gotasslum carbonate (catalyst) 10 Met anolo 960 30 ProductYield, quantitative; amber colored viscous liquid. Sp. gr. 1.32'7/20/4;sap.-No. 611.

ExsMPLm IIL-Gr-xcsaor. MONOGL'YCOLATE The conditions and procedure arethe same as Example I.

Quantities Parts Moles Methyl glycolate 1, 980 22 Glycerol (90%) 2, 10822 Anhgdrous potassium carbonate.(catalyst) 10 Met anol ofl 704 22product Yield, quantitative; pale amber colored liquid. Sp. gr. 1.32060/60 F.; sap. No. 380.

Exemrnn IV.GLYOEROL Drcmrcomrr: The conditions and procedure are thesame as types of polymerized hydrocarbons, formaldehyde andurea-formaldehyde resins;

In place of the sodium methoxide of the examples, other alcoholysiscatalysts may be used such as sodium ethoxide, sodium glyceroxide, andalkali metal alkoxides generally; sodium hydroxide, anhydrous potassiumcarbonate, calcium oxide, litharge, etc.; or mixtures of the two types.Alkaline alcoholysis catalysts are, in general, more satisfactory,though in some instances, acid alcoholysis catalysts, e. g., sulfuric,p. toluene sulphonic acid, and hydrochloric acids, may be employed.

The poiyhydric alcohol esters and ether-esters of glycolic acid, as wellas the other esters described herein, have many characteristics whichparticularly fit them for uses in the arts. They are all generallyuseful as solvents or plasticizers for man natural and synthetic resinswhich are used with or without pigments, fillers, extenders and thelike, which compositions are employed for the preparation of lacquers,pigments, paste pigments, etc; or for the formation of films, filaments,rods, tubes, or shaped articles. More specifically, they are generallyuseful as solvents, plasticizers and softeners for. natural resins,such,

' for example, as dammar, copal, Kuri andfor the synthetic resins, such,for example, as the alkyds; cumarone-indene; chlorinated diphenyl;soluble phenolester gum; polymeric acrylic and methacrylic acids andtheir esters, amides, nitriles, imides, salts, interpolymers, and otherderivatives; polyvinyl alcohol; the polyvinyl esters; styrene and otherpolymeric resins, as well as simple mixtures of the' natural and/orsynthetic resins, and/or interpolymers of the polymeric resins. Thepolyhydroxy alcohol estersof glycolic acid are also useful as solvents,plasticizers or softeners of regenerated cellulose and the cellulosederivatives, such as, cellulose acetate, ni-

e,'ses,1c4

the fiow'and gloss properties of the result ns films. The ether-estershave been found acceptable as frothing agents for the flotation of oresand as solvents for the absorption of acidic gases such as the sulfuroxides. hydrogen sulfides, etc.

Furthermore, they, together with the other polyhydric alcohol esters ofglycolic acid, are excel flxativesufor perfumes; as softeners for cork.

binders, glue, gelatin, paper and textile sizes; as an ingredient indentifrice compositions;-as softeners for casein, zein, soybean, proteinplastics, etc.; as an ingredient in leak-proofing compositions for gasdistributing systems, gas masks and trate, acetc-nitrate,aceto-propionate, methyl cellulose, ethyl cellulose and otherorganicderivatives of cellulose or mixtures thereof.

The polyhydric alcohol esters of glycolic acid are likewise generallyapplicable as the major ingredients in the preparation of printing padsand ink feeders of all types, as penetrating agents for printing pastes,and as major ingredients in the preparation ofkinks', both for theprinting of paper, textiles, wood, metal or other materials.

The ethylene glycol monoglycolate, diglycolate and glycerol mono-, diandtri-glycolate, may be used as'softeners for glassine paper,'as asubstitute for glycerine in tobacco, as a softener for regeneratedcellulose and as a substitute for glycerol in printing ink compositions.They have likewise been found acceptable for the sizing of theartificial and natural silks and particularly 7 for the sizing ofregenerated cellulose filaments acid esters of the monoalkyi ethers ofethylene glycol, HOCHiCOOCHiCHaOR, as has been generally stated above,excellent solvents for cellulose ethers and cellulose esters. Thesecompositions are especially valuable in brush-type lacquers and lacquersapplied hot, as they improve the like; in the preparation of wetting,dispersing and penetrating agents, etc.,,such as sulfates and the like;as precipitation inhibitors; and as ingredients in fluidsforhydraulically actuated mechanisms.

The phosphate derivatives of the polyhydric alcohol glycolates arelikewise useful as plasticizers generally for use in combination withthe aforementioned natural and synthetic resins, as well as thecellulose ethers, esters, and regenerated forms of cellulose. v

The esters of the alkoxy acetic acids, in addition to the uses abovedescribed for the glycolic esters of the alkyl ethers of the polyhydricalcohols and because. of their large number of active solvent groups,are particularly excellent solvents for gases, liquids, solids andresins. The excellent solvent properties of materials of this type canbe attributed to the combination of ether and ester groupings. v

All glycolateesters disclosed can be reacted with an aliphatic oraromatic anhydride or acid to give, relatively water insoluble estersthatare good plasticizer-softeners. As, an example the glycerolslycolates reacted with acetic anhydride will give the triacetates ofthe three glycolates of glycerol.

From a consideration of the above specification it will be realized thatmany changes may be made in the details therein given without departingfrom the scope-of the invention or sacrificing any of the advantagesthat may be derived therefrom.

I claim:

1. Mono methcxy acetate of glycerol beta methyl ether,

CHaOCH2COOCI-I2CH(OCH:) CHaOH 2. Dimethoxy acetate of glycerolbeta-methyl ether,

CHsOCHzCOOCH2CH(OCI -Ia) CHzOOCCI-BOCH:

3. A glycerol ether ester selected from the group consisting of themono'and dimethoxy acetates of glycerol beta methyl ether.

DONALD JOHN LODER.

